The present invention relates to electrometallurgy and, more particularly, to a plant for effecting the method of electroslag melting of shaped castings.
The present invention may prove to be most advantageous in mechanical engineering for producing parts and units which should meet more stringent requirements as to their quality, such as, blanks for covers and bodies of fittings for atomic power plants, rolls for cold rolling mills, crankshafts, T-pieces and connecting rods intended to replace forged or forged-and-welded constructions of similar designation. The first lots of rolls for cold rolling mills produced on an industrial scale from metal obtained by the electroslag melting technique and tested under service conditions have proved that the service life of such rolls has been extended almost 2 or 3 times.
High quality and homogeneity of metal of ingots obtained by the electroslag process have suggested an idea about the possibility of using cast mill rolls produced by the electroslag remelting technique in shaped molds.
Known in the art are methods of producing blanks for, e.g., mill rolls, by the electroslag remelting techniques, in which a single or a plurality of metal electrodes are melted one after another in slag baths. In this case melting is accomplished at least in two cooled molds of different cross sections mounted one above another on individual jack carriages. The jack carriages carrying the molds and that mount the electrodes and arranged above the first carriages are capable of moving vertically along the masts.
The disadvantages peculiar to these methods and to the above-described plant reside in that when producing blanks differing in their cross-sectional heights, for melting blanks of each cross section it is necessary to use different electrodes and the replacement of these electrodes during the melting process causes shutdowns which adversely affect the quality of metal of the blanks being melted. Moreover, in the course of melting the amount of slag should be varied, increased or decreased, which causes inconvenience in servicing the casters.
More suitable are the methods of melting mill roll blanks by the electroslag remelting technique in a mold whose diameter corresponds to that of a roll barrel. An element to be remelted, corresponding in shape and size to a roll neck is set up in a mold on a base plate side and is fused to a base of a blank at the beginning of the process. The mold base plate has an opening whose diameter corresponds to that of the element being fused and forming the roll neck. The base plate is split vertically into two parts under which are mounted current-carrying prisms.
However, the above method and plant do not provide as well the guaranteed quality in the fusion zone wherein the element being fused is fused to the blank. Moreover, since the base plate is split vertically into two parts, it is warped owing to thermal expansion of the element being fused upon heating, and after the first heat the opening does not correspond anymore to the initial diameter of the element being fused. The resulting gap should be sealed to preclude the effluence of molten flux and metal. Thus, from one heat to another the gap between side surfaces of the base plate and the element being fused becomes larger which eventually results in a rapid failure of the base plate. Such plants are inconvenient in servicing.